Satellite communication systems typically have employed large aperture antennas and high power transmitters for establishing an uplink to the satellite. Recently, however, very small aperture antenna ground terminals, referred to as remote ground terminals, have been developed for data transmission at low rates. In such systems, the remote ground terminals are utilized for communicating via a satellite from a remote location to a central hub station. The central hub station communicates with multiple remote ground terminals, and has a significantly larger antenna, as well as a significantly larger power output capability than any of the remote ground terminals.
Typically, the remote ground terminals comprise a small aperture directional antenna for receiving and transmitting signals to a satellite; an outdoor unit mounted proximate the antenna which comprises a transmitter for producing and transmitting a modulated data signal and an amplifier for boosting the receive level; and an indoor unit which demodulates incoming signals and also operates as an interface between a specific user's communication equipment and the outdoor unit.
The installation of such remote ground terminals entails positioning the directional antenna in the direction of the desired satellite so as to maximize the amplitude of the signal received from the satellite. Various techniques have been utilized to aim the antenna. One known technique is to couple a signal level meter to the output of the demodulator of the indoor unit. The amplitude of the received signal is then monitored as the antenna positioned is adjusted. However, this technique has several drawbacks. First, it requires the use of additional equipment (i.e., the meter). Second, as the antenna is not located proximate the indoor unit, it requires the presence of two technicians to perform the installation.
U.S. Pat. No. 4,881,081 discloses a device for adjusting the antenna orientation which eliminates the need for two installation technicians. However, the device requires a substantial number of additional components which are dedicated exclusively for the purpose of antenna orientation.
As the viability of the remote ground terminal concept increases as the cost for providing the remote ground terminal at the remote location decreases, it is necessary to decrease the cost of the remote ground terminal as well as the costs associated with the installation thereof as much as possible.
Accordingly, to minimize the costs of purchasing and installing a remote ground terminal, there exists a need for a remote ground terminal which can be installed by a single technician and which does not require additional components dedicated exclusively for the purpose of positioning the antenna to be included in either the indoor unit or the outdoor unit. Further, there exists a need for a remote ground terminal whose installation procedure does not vary from unit to unit due to effects of temperature or operational characteristics of components.